1. The question asks if the interval for 3 is $(-\infty,0) \cup \{0\} \cup (0,+\infty)$. 2. This notation means all real numbers except possibly how 0 is treated (open or closed). 3. Since $(-\infty,0)$ is open at 0, $\{0\}$ is the single point 0, and $(0,+\infty)$ is open at 0, their union covers all real numbers. 4. So yes, the union $(-\infty,0) \cup \{0\} \cup (0,+\infty)$ equals $\mathbb{R}$, the entire real line. 5. Therefore, the answer to your question is **yes**.